Not what it's made out to be.
You NEED the hub otherwise buy a basic flap. Without the hub - only set indoor/outdoor access. Change - de-register and register cat/s each time individually. Certainly not practical when you want cats to stay in at night and go out during the day. and/or have different permissions depending on each cat. To top it off you need to position the hub within line of sight of the hub AND connect it to your router at the same time.....a feat nigh on impossible in most households.